Combined screw and lock washer



' Jan. 20, 1942. J. J. ToMAUs COMBINED SCREW AND LOCK WASHER Filed Feb. 2'7. 1939 v, the screw is inserted, the washer directly to the screw shank; I

- Patented Jan. 20, 1942 COMBINED SCREW AND LdCK WASHER Joseph J. Tomalis, Providence, R. I., assignor to American Screw Company, Providence, R. 1., a

I eorporationoi' Rhode Island ;liggflgm mmry 27, 1939, Serial No.

(Cl. its-5) 2 Claims.

This invention relates to acom'bination of a s jfiw or bolt and, a lock washer, particularly a "lock washer of the general type which includes an annular central portion having external radial teeth which are twisted or offset to engage the underside of the screw, head and the work piece in which the screw is inserted. The hole in the washer is threaded internally to fit the threads cut or rolled on the shank of the screw and the washer is attached to or firmly combined with the screw by means of additional or supplementary helical threads formed on the shank of the screw near the head thereof, such supplementary threads being cut or formed by the washer itselfas the washer and screw are rotated relative to each other. One'purpose of the invention is to provide a combination of the kind described in which the screw and washer can be combined and sold as a pro-assembled unit and'in which the parts are so firmly secured together as to. prevent axial separation thereof before being used. A further object is to form a combination of screw and washer which, when in position on the worlnwill serve to prevent any shifting orrelative movement %tween the screw and washer even under extreme conditions of vibration, and which will thus function more effectively in securing together parts of machincry and the like where extreme vibration occurs. These and other advantages of the in ention will more fully appear hereinafter.

The following specification and the accompanying drawing forming a part hereof will serve to disclose the nature of the invention andvarious applications thereof. In said drawing,

ure 7 is a sectional view similar to Figure 6, but showing a conventional lock washer not locked to the screw shank; and

Figure 8 is a longitudinal section of a modified arrangement in which the,shank-of--the-screwis enlarged adjacent the head, the washer being mounted on such enlarged portion by supplemental threads formed thereon.

In applying the invention in practical use, a thin flat lock washer of the kind shown at H) in the various figures is preferably employed.

" This type of washer, which is well known in the I as to enclose the entire outside diameter of the Figure 1 is a plan view ofa lock washer of the kind preferably employed in producing the combination forming the invention;

Figure 2 is a transverse section on the line 2-2 of Figure l, and Figure 3 is a similar section on the line. li -ii of Figure l;

Figure 4 is a longitudinal side view of ascrew having working threads thereon and a threaded washer moved partly along the working threads thereof;

Figure 5 is a side view similar to Figure 4, but showing the washer advanced along-the screw shank until the washer has cut or formed additional helical threads on the screw shank and is tightly engaged against the screw head;

Figure 6 is a section showing a screw and washer in assembled relation with parts in which being locked art, is provided with an annular body'portion IDA and radially projecting prongs or teeth IUB' which are bent or twisted to form sharp corners for engaging the bottom of the screw or bolt head and the work and thus prevent rotation of the screw. zAccording to the present invention, the hole in the washer, is internally threaded to fit the working thread cut or rolled on the screw or bolt to which the washer is applied.

As ordinarily made, the thickness of the washer is such that only part of one thread maybe formed in the hole, but such a partial thread will'serve the purposes of the invention. The threaded hole in the washer may be made in the form of a regular V-point thread as indicated at I BC in Figure 2, each thread lilC extending substantially half way aroundthe periphery of the hole and terminating at diametrically opposite points indicated at ND. The diameter of the hole between these points is such screw, plus necessaryclearance. For use with screws having cut threads, the threads WC of the washer may be made of a diameter substantially equal to the root diameter of the work 'ing or punching, rather than by tapping a thread therein. However, in thicker washers it may be necessary and desirable to tap the thread'in which case the hole wouldhave a complete thread all around.

In producing washers of the kind described, they are preferably formed of high carbon steel material and subsequent to the forming thereof, they are heat treated so as to possess live action or spring action, and when thus treated, the

ates g J V thread of the washer iscapable of cutting or forming helical threads in softer material such as usually employed in making screws and bolts.

with ordinary methods of screw manufacture, the working thread is cut or rolled on the shank of the screw so that a portion of the shank be tween the thread and the underside of the head is left unthreaded. In the various views of the drawing the screw is indicated at i i, the work ing threads at 12 and the unthresded per tion of the shank is shown at H in Figure 4, such unthreaded portions usually being more extensive in rolled thread products. On a cut thread screw or "colt, this unthresded portion of the shank is generally of a diameter equal to the major indicated Figure 4;.

thread pr such unthreeded genera-l he a diameter equal to the pitch. 'i

fi previously noted, invention pres nts principal escects. it he employed in forming a combin crew and washer assembly which may ma. sold as an article of manufacture; 2'5 may be employed in any relation where e. inserted in a work piece and where iris essential to guard against loosening of the screw by ibration.-

EJhve it is 21 d to form a screw and washer or by reason of. threaded enced along the w! e indicated Fish tied shculder At rec-lei: the in any suitable manner station of the will out -r ie'seter of the working thread, as

un il it coir-L o the washer efieccive means for e the screw so assembled ccnditicr:

ready s 1 aesied. The procedure 1 famine assembly of e. a o having is rolled thread.

in emerge in Figure 8, the

shank is eels. get, at as, end such e and the a-nja i; the head as indicated ergement may be unthreeded '"""med with a hole of proper large-mania and with threads chereiz's. which form additional helical threads its on the enlargemen whereby the washer wilibe firmly against axial nevement en the screw.

It will thus be seen that the invention may be utilized to produce various forms of pre-as s screwand lock washers in which the washer is firmlymcunted on and secured to the screw shank by means of helical threads cut or formed thereon by the washer itself.

As previously noted, the invention has particular utility in providing means for flrmly holding a screw .in a piece of work, even under extreme conditions of vibration. This is illustrated inFigures 6 and 8 of the drawing, in each of Fri case 05- rollezl work piece and the screw head. A rare-assembled screw and washer as above described may be used and the screw may be threaded into the work until the washer is tightly clamped between the 5 two. If a screw and lock washer not previously assembled are to be used, the washer may be advanced along the thread of the screw ii until it contacts the unthreadecl portion i3 thereof, which may be done before the screw is inserted in the work or during the operation of inserting the same. when the threaded portion or the washer contacts the unthreaded portion of the screw and the face of the washer engages the we a: piece, it will be seen that further retatlcn cf the screw will cause the washer to out or form additional heliealjshgeaw in the 1 .n-

tmeeded'sh anh of the screw and advance toward h ad of the screw until is securely ehrnped tlen with teeth of mg hath the work piece and the head, es'shce n at and various times of the drawing. In other words, in such an assemblage, i washer screw and work piece will be licensed together at three of contact, namely, ight engagement between the washer and the s eel threads formed on screw sin-n by the teeth int A seen inleuhc a.

r trans arse s1 e screw relative the Y er so the screw r tip locked in ice. in the work vihmtion. In

1 armneem x e: is more or i share; as hicicsted at 3 will ilfilmii? relative mewh ch not firmly n which these coed, e t as ates-tire only. In actual one: found that the internal threads of actually cut away or remove little or metal of the screw shank, but merely serve ts displace or force aside the metal of he shank to form the helical grooves or threads M; Having thus described invention, what is claimed as new and desired 'tc be secured by Letters Faient is:

i. As an article of manufacture r. ecmhincd screw lock washer comp: mg a sc ew haw ing a head and a shank, said hank has, cg helical working threads formed thereon w i tenninete at a point spaced from e and cf field head, a washer mounted on i at; par non ct said shank adjacentsaid head, said washer having a hole therein provided with internal threads shaped to cooperate with the working threads on said shank, whereby said washer may be rotated along said shank, said shank having supplementary threads on the portion thereof between said.

working threads and the underside of said head and on which said washer is firmly mounted, said supplementary threads being formed on the screw shank by relative rotation between said washer and shank, and constituting means for.

frictionally securing the washer on the screw shank adjacent said head.

2. A combined screw and lock washer comprislenient-cry helishank having working threads thereon which terminate at a point spaced from the underside of said head, a washer mounted on a portion of said shank adjacent said head; said washer 6 having a 'hole therein provided with internal threads shaped to iit and cooperate with the working threads on said shank. whereby said washer may be rotated along said shank, said is,27o,sso r 3 ing' a screw a'head and a shank, saidof the shank, meansfor securing said washer on said portion of the shank adjacent the screw head, said means" comprising supplementary threads formed on said portion of the shank by the threads in said washer due to relative rotation of the washer and shank, the washer being mounted on and firmly secured to said supplementary threads by frictional engagement therewith.

JOSEPH .1. 'r ouama, 

